1. Field of the Invention
The present invention relates to solving emissions problems, particularly of sulfur compounds, from improperly prepared drywall (gypsum board).
2. Background Art
“Chinese Drywall” has been used to refer to defective or tainted drywall imported from China from 2001 to 2007 which emits sulfur gases which usually create a noxious odor and corrode copper and other metal surfaces, thereby damaging air conditioners, electrical wiring, copper plumbing, appliances and electronics. Chinese drywall can also cause adverse health effects, although experts disagree whether these effects are merely irritants or present a more imminent or chronic health hazard. Not all drywall manufactured in China is defective, and it is believed that drywall exhibiting the same problem has also been produced domestically.
While the material source of the problem is known, a complete understanding of the cause of the problem remains unknown, which is likely due in part because different mines were involved, there were different manufacturing processes, and different types of construction and building materials were used.
Initially, the most common theory was that the drywall was manufactured in gypsum mines in China and also incorporated fly ash, a waste material that is a byproduct from power plants using coal. Samples of Chinese drywall tested by United Engineering, however, consisted of 5-15% organic material, which contradicts the theory that Chinese drywall was made of waste from coal fired power plants. It is now believed that the tainted drywall from China comes from mined gypsum, not synthetic gypsum which is made from coal ash. Mined gypsum contains high levels of strontium, which is visible as inclusions in electron scanning microscopy.
Another theory is that Chinese drywall contains bacteria (possibly from the water source used to manufacture the drywall) which degrades iron and sulfur compounds to produce sulfur odors, although the CPSC's recent report disputes this theory.
There is no question that the gasses emitted from Chinese drywall corrode copper and metal surfaces. Corrosion of electrical wiring may hamper the effectiveness of smoke detectors, which clearly presents a safety concern. Low level arcing has also been observed in some homes with Chinese drywall, which could cause an electrical fire.
Chinese drywall was found by Lawrence Berkely National Laboratories to emit hydrogen sulfide up to 100 times greater than conventional drywall. Hydrogen sulfide is a hazardous gas which, in high concentrations, can be fatal. There is also a strong association between hydrogen sulfide and metal corrosion. Analytical testing of Chinese drywall samples have revealed strontium sulfide, although there remains disagreement regarding whether strontium is a valid marker for Chinese drywall. According to Dr. Patricia Williams, a University of New Orleans toxicologist, highly toxic compounds have been found in Chinese drywall and prolonged exposure to these compounds can cause serious problems.
Strontium sulfide may be dangerous to developing children, as it affects bone growth. Chronic exposure to sulfur-containing gases may affect the central nervous system (including visual and sensory changes), cardiovascular system, eyes, kidneys, liver and skin. Infants, children, the elderly and infirm (particularly those with heart and lung disease and diabetes) and pets may have an increased vulnerability to these gases and the particulates that are released from the drywall. To date, the Florida Department of Health still maintains that the levels found in Chinese drywall are not high enough to present “an imminent or chronic health hazard at this time.” Many experts disagree.
Chinese drywall is very friable, which means it is in a state where small particles can easily become dislodged with little friction. For this reason, even after Chinese drywall is removed, the toxic drywall particulate may remain unless property removed. Further, the particulate from Chinese drywall may invade and adhere to other building materials in the home's structure and personal objects within the home. Thus, cross-contamination should be factored into any remediation protocol. According to the Florida Department of Health, it is possible for gases to be absorbed and to be re-emitted from porous materials such as drywall and fabrics. The effectiveness of cleaning these materials is currently unknown. It is also unknown whether there is any effect on concrete and lumber.
Hundreds of millions of sheets of Chinese drywall were imported from 2004 to 2006, but Chinese drywall has recently been found in homes built or remodeled as early as 2001. Accordingly, this phenomenon cannot be explained solely by the shortage of American-manufactured drywall. The presence of Chinese drywall has been reported in 37 states, the District of Columbia and Puerto Rico, and is estimated to have been installed in over 100,000 homes in the United States. Unfortunately, this does not paint an accurate picture as most affected homes have a mixture of safe and tainted drywall.
Chinese drywall is ½″ in width, although according to Lori A. Streit, Ph.D., from Unified Engineering, the same compounds found in problematic Chinese drywall and the same gases released from there have also been found in drywall measuring ⅝″ (which is typically used in ceilings). Chinese drywall is typically mixed in with untainted drywall, which is why people should not assume that their home is fine if they find U.S. drywall. Moreover, U.S. drywall may have been manufactured in China and rebranded.
One of the telltale signs of Chinese drywall is corrosion/pitting of the air conditioner evaporator coils (which are located inside the air handler). Many owners are first advised of a freon leak, and as the corrosion progresses, evaporator coils eventually need replacement. An examination of the coils typically (but not always) reveal a black sooty deposit, which may also appear on the Freon line.
Chinese drywall also corrodes electrical wiring, as shown by blackened ground wires. Since many homes have mixed drywall (i.e. good and bad drywall), not all ground wires will show blackening. Signs of electrical problems include circuit breakers which frequently need resetting without an apparent cause (particularly a GFCI or AFCI); lights that flicker without any apparent cause; bright flashes or sparks anywhere in the electrical system (this may indicate arcing conditions in the wiring); buzzing from electrical systems, switch plates, dimmers, and outlet covers that are discolored from overheating; and a smell from overheating plastic.